The present invention relates to a combination electrode for the measurement of PH. For the measurement of PH by the method of electrode potential, since it is necessary to use a glass electrode and a reference electrode, a combination electrode which is a combination of the said two electrodes into a body has been widely used. In this case, a glass membrane which is the most important part of the electrode, is delicate and easily damaged and accordingly, it is necessary to change or replace it very often. Since the said combination electrode is a combination of two electrodes, a glass electrode and a reference electrode, into a single body, when the glass membrane is damaged or abraded and becomes impossible to use further, it is necessary to exchange the whole combination electrode itself. This is a serious disadvantage of the said combination electrode. In order to overcome such a disadvantage, devices have been proposed, for example, such as disclosed in Japanese Utility Model Application published as 19657/1967, wherein the outside tube has the specific shape of the letter Y, which is very inconvenient for use or for storage. Moreover, in the cited Japanese Utility Model Application, when the glass membrane is damaged, even if it is possible to exchange the glass electrode, it is also necessary to change the out-side lead wire to be connected to a detector (a voltmeter), since the lead wire is attached to the glass electrode in a unitary body.